feat: Add App Version to UI

invokeai/app/api/routers/app_info.py

@@ -0,0 +1,18 @@
+from fastapi.routing import APIRouter
+from pydantic import BaseModel
+
+from invokeai.version import __version__
+
+app_router = APIRouter(prefix="/v1/app", tags=['app'])
+
+
+class AppVersion(BaseModel):
+    """App Version Response"""
+    version: str
+
+
+@app_router.get('/version', operation_id="app_version",
+                status_code=200,
+                response_model=AppVersion)
+async def get_version() -> AppVersion:
+    return AppVersion(version=__version__)